Deflectors have a number of uses in devices that employ charged particle beams. For example, in scanning electron microscopes, deflectors are employed for the high-speed and high-precision scanning of an electron beam on a specimen. Deflectors are also used in charged particle beam transfer devices used, for example, in the reductive transfer, by electron beam, of a mask pattern onto a substrate surface (e.g., for transferring features, defined by a reticle or mask, onto the surface of a semiconductor wafer). For example, in such devices, a subfield-selection deflector is used to direct an electron beam onto a mask subfield (among multiple subfields comprising the complete mask pattern) to be transferred to the wafer surface. In addition, in such devices, deflectors are used to guide the electron beam, after having passed through a mask subfield, to the corresponding region on the wafer substrate.
The most recent generation of deflectors for uses such as described above are so-called electrostatic deflectors, which are able to deflect electron beams or ion beams at high speeds and with high precision. Electrostatic deflectors can be used in place of electromagnetic deflectors or in addition to electromagnetic deflectors in a device.
FIG. 5 shows an example of a conventional hexapole electrostatic deflector in which six longitudinally extended electrodes 9A-9F are arranged equilaterally around an axis AX of an electron optical system (not shown). Each of the electrodes 9A-9F is defined by a respective conductive body shaped as longitudinal segment of a hollow cylinder extending along the light axis AX. During operation, variable voltages, for example, of opposing polarities are impressed on each opposing pair of electrodes (e.g., electrodes 9C and 9F). Selectively applying voltage to the electrodes in such a manner causes an electron beam EB, for example, passing longitudinally through the space surrounded by the electrodes 9A-9F to be deflected in the desired direction relative to the axis AX.
According to one prior-art method for making the type of electrostatic deflector shown in FIG. 5, a columnar or cylindrical member made from, e.g., a copper alloy sheet is fastened circumferentially with mounting screws to a cylindrical ceramic member. The sheet is then cut into respective multiple electrodes using cutters or the like. Unfortunately, electrodes made in this manner are thick and are thus prone to exhibit substantial eddy currents during use in a time-varying magnetic field. Such eddy currents prevent the electrodes, when used in an electromagnetic lens or electromagnetic deflector, from producing a sufficiently rapid switching or change in magnetic field.
According to another prior-art method for making an electrostatic deflector, especially such deflectors that are arranged inside electromagnetic lenses or electromagnetic deflectors, multiple electrodes are formed by partially coating the surface of an insulator with a metal. When making electrodes using this method, difficulty is frequently experienced in obtaining the required accurate angular orientation of the electrodes relative to each other in multiple-pole deflectors, for example.